=over

=item shmread ID,VAR,POS,SIZE
X<shmread>
X<shmwrite>

=item shmwrite ID,STRING,POS,SIZE

Reads or writes the System V shared memory segment ID starting at
position POS for size SIZE by attaching to it, copying in/out, and
detaching from it.  When reading, VAR must be a variable that will
hold the data read.  When writing, if STRING is too long, only SIZE
bytes are used; if STRING is too short, nulls are written to fill out
SIZE bytes.  Return true if successful, false on error.
L<C<shmread>|/shmread ID,VAR,POS,SIZE> taints the variable.  See also
L<perlipc/"SysV IPC"> and the documentation for
L<C<IPC::SysV>|IPC::SysV> and the L<C<IPC::Shareable>|IPC::Shareable>
module from CPAN.

Portability issues: L<perlport/shmread> and L<perlport/shmwrite>.

=back